A conventional power supply rectifies its ac input to supply a dc voltage to a load. A video cassette recorder ("VCR") has several power supplies or rectifiers incorporated therein to generate dc operating voltages. For instance, a 12 V dc operating voltage is utilized in such loads as an audio apparatus, a capstan motor and the like built in the VCR. The audio apparatus may be dictated to block the flow of audio signals therefrom to a loudspeaker, which state is sometimes called "audio mute". The audio mute state is set by the action of an appropriate control unit which issues an audio mute control signal to the audio apparatus so as to mute annoying noises or sounds which can be heard, e.g., when the VCR is in a certain operating mode such as Fast Forward, Still, Slow, Que and Review.
In the audio mute state, the output audio signal from the audio apparatus is blocked; however, the dc operating voltage from its power supply continues to be supplied to the audio apparatus, resulting in a waste of electric energy. Further, the capstan motor may consume an extra electric power so as to, e.g., accelerate the tape travel speed during, e.g., Fast Forward operating mode. Thus, in order to cope with an uneven power supply requirement by the capstan motor during said certain operating mode mentioned above due to abrupt changes in the tape travel speed, the power supply should be preferably designed to possess an extra capacity sufficient to satisfy the additional power consumption requirement of the capstan motor. Therefore, it is desirable to save the electric energy which may be otherwise wasted by the audio apparatus so that the saved energy can be used to accommodate the extra power requirement demanded by the capstan motor during that certain operating mode which is accompanied by an audio mute state.